Silica reinforced rubber compositions of improved processability and storage stability

ABSTRACT

The disclosure relates to a process for improving the processability, storage stability and/or cure rate of an uncured silica reinforced rubber composition where silica comprises the major filler in the reinforced rubber composition, which comprises combining a mixture comprising, rubber, silica and at least one organic compound having a low molecular weight and a functional group wherein said functional group is at least an epoxy group, such as an epoxy/ether, epoxy/hydroxyl, epoxy/ester, epoxy/amine, ether/amine, episulfide, episulfide/ether, episulfide/hydroxyl, episulfide/ester functional group located in a terminal or sterically unhindered position in the molecule of said organic compound where the molecular weight of said organic compound having a low molecular weight is less than 7,000, or the organic compound comprises an abietyl, styrenated resorcinol formaldehyde, or ester hydroxyl organic compound having a hydroxyl, ester, and optionally, an ether group, such as an ester diol.

This is a continuation-in-part application of Ser. No. 09/514,641 filedFeb. 29, 2000 now abandoned incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The invention relates to silica reinforced rubber compositions of matterhaving improved processability, storage stability and or cure for use intires and mechanical goods.

BACKGROUND OF THE INVENTION

Particulate fillers such as silica, carbon black, clays, talc, calciumcarbonate, silicates (Science and Technology of Rubber, edited by J. E.Mark et al., Academic Press Inc., San Diego, Calif., 1994 p 387-469) andstarch (F. G. Corvasce et al, U.S. Pat. No. 5,672,639) have beengenerally used as reinforcing materials for rubbers to improve theirphysical properties such as modulus, tensile strength, abrasion, tearproperties, and dynamic properties.

The reinforcement of elastomers with particulate fillers such as silicaand carbon black has been extensively studied. Four majorcharacteristics of the fillers, namely particle size, morphology,aggregate structure and surface activity, influence the physical andmechanical properties of the reinforced rubber compositions. Thesecharacteristics contribute to the reinforcement of the elastomersthrough interactions between elastomers and fillers, occlusion of theelastomer in the internal voids of the aggregate and agglomeration ofthe filler aggregates in the elastomer matrix (S. Wolff & M. J. Wang in“Carbon Black, Science & Technology,” editors: J. B. Donnet, R. C.Bansal & M. J. Wang, Marcel Dekker, Inc., New York 1993). It is knownthat several types of interactions exist between molecules which areclose to one another, e.g., dispersive, dipole-dipole, induceddipole-dipole, hydrogen bonding and the like. Such interactions canresult in different types of cohesive forces. The surface energy of asolid, Y_(s), can be expressed as the sum of several components, eachcorresponding to a specific type of interaction. For most substances:Y_(s)=Y_(s) ^(d)+Y_(s) ^(sp) where Y_(s) ^(d) is the dispersivecomponent of the surface free energy and Y_(s) ^(sp) (or specificcomponent) is the sum of the other components of the surface freeenergy. It should be noted that Y_(s) ^(sp) comprises polar components,e.g., dipole-dipole, hydrogen bonding, and the like.

The difference in the surface free energy of carbon black and silicaresults in significant differences in the filler-filler andfiller-rubber interaction. Compared to carbon black, surface energies ofsilica with equivalent surface area and structure, have a low dispersivecomponent and a high specific component (M. J. Wang & S. Wolff, RubberChemistry and Technology, 65, 329, 1992). The low dispersive component(related to weaker polymer-filler interaction) has been shown to producelow modulus at high strains (S. Wolff, M. J. Wang & E. H. Tan, AmericanChemical Society, Rubber Division Meeting, Denver, Colo., May 1993). Thehigher specific component of the surface free energy of silica resultsin strong filler-filler interaction, resulting in increased viscosity ofthe rubber composition, especially at low strain rates.

The surface characteristics and hence the surface energy of silica canbe changed by surface modification, for example, when the silica surfaceis chemically modified with so-called coupling systems such as apolyfunctional organosilane, e.g., bis(3-triethoxysilylpropyl)tetrasulfide (TESPT). The specific component of the surface freeenergy (Y_(s) ^(sp)) is significantly reduced, leading to improvedinteraction between silica and rubber for improved compatibility (M. J.Wang, S. Wolff, Rubber Chemistry and Technology, 65, 715, 1992). Areduction of filler-filler interaction results in better dispersion andreduced viscosity. Compared to reinforcing carbon black, silica retardsthe cure rate of the filled composition. This retardation in cure ratehas been attributed to the adsorption of curatives on the silica surface(M. Fetterman, Rubber Chemistry and Technology, 58, 179, 1985).

The silanol content, the adsorbed water content and the surface area ofthe silica, also affect the cure time (S. Wolff et al., AmericanChemical Society, Rubber Division Meeting, Denver, Colo., May 1993; M.P. Wagner, Rubber Chemistry & Technology, 49, 703, 1976). Silica,because of its high specific component of surface energy, has a strongtendency to agglomerate and is difficult to disperse in hydrocarbonrubbers. Polyfunctional organosilanes with sulfur linkages such as TESPTimprove interactions of filler (e.g., silica) with a polymer, therebyimproving the physical properties of vulcanizates such as abrasionresistance and reduced tan δ at 60° C. The scorch and cure times arealso affected (S. Wolff, M. J. Wang, Tyre Technology Conference, Basel1993, and Wolff et al., U.S. Pat. No. 4,229,333; Thurn et al., U.S. Pat.No. 3,873,489; Wideman et al., European Patent Application No. EP0780429A1; R. J. Pickwell, Rubber Chemistry and Technology, 56, 94,1983; K. J. Sollmann et al., Rubber Division Meeting, American ChemicalSociety, Cincinnati, Ohio, Fall 1972).

Epoxidized natural rubber (ENR) with up to 50 mole percent epoxidationhas been used alone and in combination with other diene rubbers such asnatural rubber, styrene butadiene rubber, or butadiene rubber at levelshigher than 30 phr (parts per one hundred parts of rubber, on a weightbasis) with precipitated silica and mixture of silica with carbon blackto improve wet skid resistance, but with poor tire tread abrasion andtear properties. The use of epoxidized natural rubber was accompanied byincreased viscosity, retardation of cure rate and poor processability onstorage (“Natural Rubber Science and Technology,” edited by A. D.Roberts, p.359-456, Oxford University Press, UK,1988; S. Varughese etal., Kautschuk Gummi und Kunststoffe, 43, 871, 1990). ENR, because ofthe higher mole percent epoxide groups (10-50%), is reinforced by silicaeven in the absence of coupling systems such as TESPT orγ-mercaptopropyltrimethoxysilane. The addition of a coupling systemenhances the cure rate and strength properties of silica-filled ENR(10-50 mole % epoxidation). (M. Nasir et at., European Polymer Journal,25, 267, 1989; S. Varughese and D. K. Tripathy, Journal of AppliedPolymer Science, 44, 1847, 1992). Epoxidized natural rubbers with anepoxy content from 15 to 85 mole percent have been reportedly used inblends with other diene rubbers such as polyisoprene, butadiene,carboxylated nitrile at a 1-15 phr level in silica or silica/carbonblack reinforced tread compositions. A synergistic effect of ENR with acarboxylated nitrile was reported to improve vulcanizate properties(Sandstrom, U.S. Pat. No. 5,489,628).

ENR at 5-30 phr was also reportedly used in blends with diene rubber anda coupling system (TESPT) to improve the abrasion and adhesionproperties of the vulcanizate. (Segatta et al, U.S. Pat. No. 5,396,940).The addition of glycols, amines or guanidines to rubber compositionscontaining silica has been reported to counter the retarding effect ofsilica on the cure rate during vulcanization. Addition of diethyleneglycol or triethanolamine in silica-filled rubber reduced the Mooneyviscosity and scorch time. The reduction in Mooney viscosity was storagetemperature dependant and was not apparently effective at higher storagetemperature (M. P. Wagner, Rubber Chemistry and Technology, 49, 703,1976). Diene rubber compositions with excellent processability andimproved dispersibility of silica have been claimed whendicyclohexylamine and diene polymers modified with —COOH, epoxy, aminoor hydroxyl group are used in the rubber composition (H. Takamata etal., Japanese Patent No. JP 07292159). Epoxidized soybean and linseedoils have been reported to enhance the adhesion properties of rubbercompositions, containing carbon black as major filler and silica asminor filler, with steel cords. No significant effects on viscosity andprocessability of compositions containing epoxidized soybean and linseedoils were reported with the aforementioned filler blend (Stevens et al.,DE 19700967A1, Jul. 16, 1998).

Accordingly, it would be an advantage to provide a process for reducingthe cure time and improving the processability of an uncured silicacontaining rubber composition as well as providing an uncured rubbercomposition having improved cure time and improved processability. Itwould also be an advantage to provide a silica containing cured rubbercomposition produced by the foregoing process, or a silica containingrubber composition having the foregoing properties.

These and other advantages are obtained according to the presentinvention which comprises a process, product obtained by the process,and a composition that substantially obviates one or more of thelimitations and disadvantages of the described prior art processes,products, and compositions.

The present invention comprises a process for manufacturing an uncuredsilica containing rubber composition having improved processability,improved resistance against the decay of processability during storageof the uncured stock and in some cases reduced cure time by combiningthe rubber with a class of organic compounds that impart theseproperties to the rubber composition. The invention also relates touncured or cured silica containing rubber compositions produced by theprocess of the invention and uncured and cured silica containing rubbercompositions having these organic compounds.

Additional features and advantages of the invention will be set forth inthe written description which follows, and in part will be apparent fromthe description, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the process, product-by-process and composition particularlypointed out in the written description and claims hereof as well as theappended drawings.

SUMMARY OF THE INVENTION

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described, the invention inone aspect comprises a process for improving the processability, storagestability and in some cases cure rate of silica reinforced rubber,compositions comprising the step of incorporating into said silica andrubber appropriate amounts (preferably less than about 10 phr) of atleast one organic compound, such as an organic compound comprising arelatively low molecular weight organic compound (i.e., a molecularweight of from about 50 to less than about 7000, and especially fromabout 100 to about 2000) containing at least one functional group(preferably not intramolecularly reactive) and located in terminal orsterically unhindered positions on the molecule, selected from an epoxyfunctional group, such as an epoxy/ether, epoxy/hydroxyl, epoxy/ester,epoxy/amine, ether/amine, cycloaliphatic ether/hydroxyl, episulfide,episulfide/amine, episulfide/ether, episulfide/hydroxyl orepisulfide/ester group. These compounds contain aliphatic and/orcycloaliphatic groups. Aliphatic groups comprise both saturated andunsaturated branched chain or straight chain alkyl groups, whereascycloaliphatic groups include both saturated and unsaturated ringstructures based on carbon, or heterocyclic ring structures based oncarbon that contain, in addition to carbon in the ring, oxygen, orsulfur, or nitrogen.

The organic compound also comprises abietyl compounds and especiallyabietyl amine compounds, styrenated resorcinol formaldehyde epoxypolymer compounds, or ester hydroxy organic compounds that contain atleast one hydroxyl and especially at least about two hydroxyl groups andat least one ester or one ether group, and combinations of any of theforegoing organic compounds.

In its broadest aspect, the process of the invention comprisesincorporating the low molecular weight organic compound into the silicareinforced rubber by combining a mixture comprising rubber, silica andat least one organic compound as described herein in any sequence, i.e.,it involves not only the addition of the organic compound to rubberalready containing silica but also combining rubber, silica and theorganic compound in any sequence or simultaneously.

The invention also comprises a product made by the aforesaid processincluding both uncured and cured rubber compositions and a compositionof matter containing such organic compounds in a silica rubbercomposition, including both uncured and cured compositions of matter.

In another embodiment, the invention comprises uncured and cured rubbercompositions used in tire, curing bladder and mechanical goodsapplications, and reinforced with silica or silica in combination withminor quantities of other particulate fillers such as carbon black,clay, silicates, and starch with —OH, —O—, or ester functionalities.

In a further embodiment, the invention comprises rubber compositionscombined with certain specific abietyl, styrenated resorcinolformaldehyde, and ester hydroxy organic compounds that contain at leastone hydroxyl and especially at least about two hydroxyl groups and atleast one ester or ether group, found to improve the processability andstorage stability of uncured silica reinforced rubber compositions.These ester hydroxy compounds generally comprise ester diols where theester, ether and hyroxy groups comprise functional groups. The additionof these organic compounds surprisingly lowers the viscosity and alsoreduces the rate of increase of the viscosity of the uncured rubbercomposition as a function of storage time, compared to a controlcomposition with none of these organic compounds.

The invention also comprises silica containing tire compositions such asthose used in tread, tread cushion, sidewalls, carcass, belt, overlay,liner cushion, innerliner and bead area construction made from theaforesaid rubber compositions. In another aspect the invention relatesto the use of the aforementioned organic compounds, especially epoxycompounds that reduce the cure time and increase the processability ofrubber compositions.

The uncured rubber compositions of the invention containing silica orsilica in combination with minor quantities of other particulatefillers, e.g., carbon black, clay, and the like, for use in tirecompositions, have improved processability, storage stability and insome cases cure time. The organic compounds of the invention providethese enhancements in processing and/or cure properties.

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the written description serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section of a tire employing the composition of theinvention;

FIG. 2 shows the effect of additives on Tan δ measured at 1 Hz and 0.1%strain as a function of temperature for silica-filled rubbervulcanizates employing the organic compounds of the present invention;

FIG. 3 is a graph showing the effect of additives on G′ measured at 1 Hzand 0.1% strain as a function of temperature for silica-filled rubbervulcanizates employing the organic compounds of the present invention.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory andfurther, the following description is intended to provide a moredetailed explanation of the invention as claimed.

DETAILED DESCRIPTION OF THE INVENTION

In the practice of the invention, the low molecular weight organiccompound of the invention is employed as an ingredient in uncured silicareinforced rubber compositions to improve their processabilitystability, and/or cure kinetics, without significantly affecting thephysical and dynamic properties of the vulcanizate or cured rubbercompound.

Silica reinforced compositions comprise rubber compositions containingprecipitated silica, pyrogenic silica, and silicates and combinationsthereof, where silica is present as the major filler. Other fillers usedin combination with silica comprise carbon black, clay, talc, calciumcarbonate, calcium sulfate, bentonite, titanium dioxide and starch andcombinations thereof. Pyrogenic silica and silicates are less desirable.

Useful low molecular weight organic compounds of this invention(molecular weight less than about 7000, or those having a molecularweight from about 50 to less than about 7000 and especially from about100 to about 2000) comprise the following, compounds and combinationsthereof:

N,N-diglycidyl aniline;

N,N-diglycidyl-4-glycidyl oxyaniline;

Glycidyl aniline;

Tris(2,3-epoxy propyl)isocyanurate

Oxiranemethanamine, N-(2,6-diethylphenyl)-N-(oxiranylmethyl)-(9Cl)

63804-34-2

Component Number 1

Component Number 2

Oxiranemethanamine,N,N′-(methylenedi-4,1-phenylene)bis[N-(oxiranylmethyl)-, polymer with4,4′-sulfonylbis(benzenamine](9Cl)

34229-69-1

Component Number 1

Oxiranemethanamine, N,N′-(methylenedi-4,1-phenylene)bis-,homopolymer(9Cl)

38604-99-8

2-Propanol,1,1′-[(1-methylethylidene)bis(4,1-phenyleneoxy)]bis[(3-[(oxiranylmethyl)phenylamino]-(9Cl)

Component Number 2

Component Number 3

2,6-Naphthalenedicarboxylic acid, dihydrazide, polymer withN-(oxiranylmethyl)-N-phenyloxiranemethanamine andN,N,N′,N′-tetrakis(oxiranylmethyl-1,3-benzenedimethanamine(9Cl)

51910-69-1

Component Number 1

Component Number 2

H₂N—CH₂—CH₂—NH₂

1,2-Ethanediamine, polymer withN-(oxiranylmethyl)-N-phenyloxiranemethanamine(9Cl)

38605-00-4

2-Propanol,1,1′-[1,4-phenylenebis(oxy)]bis[3-[(oxiranylmethyl)phenylamino]-(9Cl)

Glycidyl vinyl benzyl ether;

Glycidyl(2,3-epoxy-1-propenyl)

Glycidyl vinyl ether;

2-Methyl-2-vinyl oxirane;

Vinyl glycidyl chalcogenides

1,2-Epoxy decene;

1,2-Epoxy-9-decene;

2-Butenedioic acid (2Z)-, sodium salt, polymer with 1,3-butadiene,ethenylbenzene, 2,5-furandione, 2-methyl-1-propene and2,2′,2″-[1,2,3-propanetryltris(oxymethylene)]tris[oxirane], block(9Cl)

110713-42-3

Component Number 1

Component Number 2

Na

Component Number 3

H₂C═CH—CH═CH₂

Component Number 4

H₂C═CH—Ph

2-Propenoic acid, sodium salt, polymer with 1,3-butadiene,ethenylbenzene and2,2′,2″-[1,2,3-propanetriyltris(oxymethylene)]tris[oxirane], block(9Cl)

119692-59-0

2-Propenoic acid, 4-(oxiranylmethoxy)butyl ester(9Cl)

1H-indole, 1-ethenyl-4,5,6,7-tetrahydro-, polymer with[[2-(ethenyloxy)ethoxy]methyl]oxirane(9Cl)

2(D1-Me)

Component Number 2

Oxirane, [[methyl-2-[methyl-2-(2-propenyloxy)ethoxy]ethoxy]methyl]-,polymer with oxirane(9Cl)

Polyglycidyl ether of castor oil;

Dimer acid diglycidyl ester;

Vinyl glycidyl chalcogenides and combinations thereof.

The vinyl glycidyl chalcogenides comprise those where the chalcogencomprises oxygen, sulfur, selenium or tellurium, and combinationsthereof, but especially sulfur or selenium, and combinations thereof.

Examples of epoxy/hydroxyl compounds comprise bisphenol A or bisphenolF-epichlorohydrin reaction products which are glycidyl end-cappedpolymers such as the EPON® compounds from Shell Chemical Co.Polyglycidyl ethers of aliphatic polyols generally comprise polyalkyleneglycol diglycidyl ethers where the alkylene group has from 2 to about 5and especially from about 2 to about 3 carbon atoms, and anywhere fromabout 2 to about 1000, and especially from about 2 to about 500, andpreferably from about 2 to about 10 repeating polyalkylene glycol unitssuch as polypropylene glycol (3 moles) diglycidyl ether.

Examples of the dimer acid diglycidyl ester comprise diglycidyl estersof 3-hydroxypropylene oxide or 3-hydroxypropylene sulfide and aliphaticor cycloaliphatic acids (as those terms are defined herein) havinganywhere from 2 to about 20 carbon atoms and especially from about 2 toabout 10 carbon atoms such as the dimer acid diglycidyl ester AldrichChemicals No. 43, 030-7 (Aldrich Catalog 1998, 1999 incorporated hereinby reference).

The polyglycol diepoxides include compounds such as glycerol diglycidylether, or diglycidyl ethers of polyhydroxy aliphatic compounds such asaliphatic compounds having anywhere from about 3 to about 6 carbon atomsand from 3 to about 6 hydroxyl groups well known in the art, butpreferably glycerol diglycidyl ether.

Polypropylene glycol diglycidyl ether;

Isopropylglycidylether;

3,4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate;

Diglycidyl-1,2-cyclohexane dicarboxylate;

2,3-Epoxypropyl benzene;

Exo-2,3-eoxynorbornane;

Poly(bisphenol A-co-epichlorohydrin)glycidyl end-capped;

Gycidyl 4-methoxy phenyl ether;

2-Ethyl hexyl diglycidyl ether;

Poly(phenylglycidyl ether)-co-formaldehyde;

Alkyl(C₈-C₁₂)glycidyl ethers;

Butyl glycidyl ether;

Cresyl glycidyl ether;

Phenyl glycidyl ether;

Nnonyl phenyl glycidyl ether;

P-tertiary butyl phenyl glycidyl ether;

Diglycidyl ether of 1,4-butanediol;

Diglycidyl ether of neopentyl glycol;

Diglycidyl ether of cyclohexane dimethanol;

Trimethylol ethane trigylcidyl ether;

Trimethylol propane trigylcidyl ether;

Diglycidyl ether of dibromoneopentyl glycol;

Polyglycol diepoxide, Mol. Wt. about 250 to less than 7,000;

Polyglycidyl ether of aliphatic polyol, Mol. Wt. about 250 to less than7,000;

1,2 Epoxy butane;

Cis & trans 2,3-epoxy butane;

1,3 Butadiene diepoxide;

3,4-Epoxy-1-butene;

1,2-Epoxy cyclododecane;

1,4 Epoxycyclohexane;

1,2-Epoxy dodecane;

1,2-Epoxy hexadecane;

1,2-Epoxy octane;

1,2 Epoxy-7-octene;

1,2-Epoxy-3-phenoxypropane;

3,6 Epoxy-1,2,3,6 tetrahydrophthalic anhydride;

1,4,Cyclo hexane dimethanol diglycidyl ether;

Cyclohexene oxide;

Neopentyl glycol diglycidyl ether;

Neopentyl glycol diglycidyl ether, brominated;

Polyethylene glycol diglycidyl ether, Mol. Wt. about 250 to less than7,000;

Polyethylene glycol glycidyl ether, Mol. Wt. about 250 to less than7,000;

Polypropylene glycol glycidyl ether, Mol. Wt. about 250 to less than7,000;

Low molecular weight (<700) epoxidized polylsoprene, polybutadiene and(poly)styrene-butadiene rubber and also with hydroxy functional groups;

Poly(ortho cresyl glycidyl ether)-co-formaldehyde];

Poly(dimethyl siloxane), diglycidyl ether terminated;

Poly(dimethyl siloxane)-co-[2,(3,4-epoxycyclohexyl)ethyl]methylsiloxane];

Trimethylol ethane triglycidyl ether;

Trimethylol propane trigylcidyl ether;

Polyglycidyl ether of castor oil;

Dimer acid diglycidyl ether;

N-(2,3-epoxypropyl)phthalimide;

9036-34-4

Poly[oxy(methyl-1,2-ethanediyl)], α-(oxiranylmethyl)-ω-phenoxy-(9Cl)

14435-46-2

Oxirane, [(2-phenoxyethoxy)methyl]-(9Cl)

19614-67-6

Oxiranemethanamine, N-ethyl N phenyl-(9Cl)

203944-15-4

Component Number 1

Component Number 2

Oxirane, [[2-(2-methoxyethoxy)ethoxy]methyl]-, polymer with oxirane,graft (9Cl)

40349-67-5

Poly(oxy-1,2-ethanediyl), α-methyl-ω-(oxiranylmethoxy)-(9Cl)

Oxirane, [[2-(2-methoxyethoxy)ethoxy]methyl]-(9Cl)

203863-90-5

Component Number 1

Component Number 2

Component Number 3

Oxirane, 2-methyl-2-[(oxiranylmethoxy)methyl]-, polymer with oxirane and2,5,8,11-tetraoxadodec-1-yloxirane, graft (9Cl)

Component Number 1

Oxirane, 2,2′-[oxybis(2,1-ethanediyloxymethylenel]bis-, homopolymer(9Cl)

54951-97-2

Component Number 1

Component Number 2

HO₂C—(CH₂)₃—CO₂H

Pentanedioic acid, polymer withα-(oxiranylmethyl)-ω-(oxiranylmethoxy)poly(oxy-1,2-ethanediyl)(9Cl)

203863-88-1

2(D1-Me)

Oxirane, 2,2′-[(dimethyl-1,3-propanediyl)bis(oxymethylene)]bis-(9Cl)

203863-92-7

Component Number 1

Component Number 2

Component Number 3

Oxirane, 2-methyl-2-[[2-[2-(oxiranylmethoxy)ethoxy]ethoxy]methyl]-,polymer with oxirane and [[2-(2-propoxyethoxy)ethoxy]methyl]oxirane,graft (9Cl)

Isopropylene sulfide;

Isobutylene sulfide;

Methyl thiirane;

1,2 Epithio-3-phenyl propane;

Thiirane-2,3-diphenyl;

Oxalic acid, 1,2-dithio-, cyclidC,S-spiro[thiirane-2,9′thioxanthen]-3-ylidene ester;

3-(Methoxy)propylene sulfide;

1-Buten-2-amine, N,N-diethyl-3-methyl-3-(thiiranylmethoxy)-hydrochloride;

1-Propen-2-amine, N,N-diethyl-3-(thiiranyl methoxy)-hydrochloride;

1-Hexene-2-amine, N,N-diethyl-3-(thiiranyl methoxy)-hydrochloride;

Epithio-1,1-bis[p-(dimethylamino)-phenyl]-2,2-bis-(p-chlorophenyl)-ethane;

3-(Diethyl)amine

9H-Purin-6-amine, 9-(thiiranyl methyl);

1-Propene-2-amine, N,N-diethyl-3-(thiiranyl methoxy)-hydrochloride;

1-Hexene-2-amine, N,N-diethyl-3-(thiiranyl methoxy)-hydrochloride;

1-Butene-2-amine, N,N-diethyl-3-methyl-3-(thiiranyl methoxy).

3-Hydroxy propylene sulfide;

Thiirane propanenitrile, β-hydroxy.

3-(Ethyl ester)-1,2-dimethyl propylene sulfide;

Spiro[9H-fluorene-9,2′-thiirane]-3-acetic acid, 3′-(methoxycarbony)-α-(phenyl amino), methyl ester;

Spiro[thiirane-2,9′-[9H]xanthene]-3,3dicarboxylic acid, dimethyl ester;

Spiro[thiirane-2,9′[9H]thioxanathene]-3,3-dicarboxylic acid dimethylester.

Glycidyl acrylate;

Glycidyl metharcylate;

Glycerol propoxylate trigylcidyl ether;

Glycidyl 3-nitrobezene sulfonate;

Glycidyl 4-nitrobezoate;

Glycidyl tosylate;

N-(2,3-epoxy propyl)phthalimide;

Poly(ethylene-co-glycidyl methacrylate), Mol. Wt. about 250 to less than7,000;

Glycidyl butyrate;

Glycidyl neodcanoate;

 HO—CH₂—CH₂—O—CH₂—CH₂—OH

HO₂C—(CH₂)₈—CO₂H

Decanedioic acid, polymer with oxiranylmethyl4-(oxiranylmethoxy)benzoate and 2,2′-oxybis[ethanol](9Cl)

Glycidyl isobutyl ether;

Glycidyl methyl ether;

Glycidyl 2-methyl phenyl ether;

Glycidyl 4-nonyl phenyl ether;

Glycidyl pentyl ether;

Glycidyl propyl ether;

Glycidyl trityl ether;

Glycidyl undecyl ether;

Glycidyl hexadecafluoro nonyl ether;

Glycidyl octafluoro pentyl ether;

Dodecyl glycidyl ether;

Tetradeycl glycidyl ether;

Furfuryl glycidyl ether;

Limonene oxide;

Poly[glycidyl 3-pentadecadizenyl);

Phenyl ether-co-formaldehyde;

The abietyl amine compounds employed according to the present inventioninclude the alkylene oxide addition products of the amines of abieticacid as well as the isomers and homologues of these amines of abieticacid, which include without limitation, the pimaric, andaracopimaric,palustric, elliotinoic and podocarpic isomers and homologues, especiallyhydrogenated or dehydrogenated abietic acid amines, and the isomers andhomologues thereof (e.g., the dehydro abietic acid amines and isomersand homologues), and include both primary and secondary amines, andcombinations thereof. These alkylene oxide addition products may beadmixed with the amines of abietic acid (as defined herein) so that thelatter may be present in amounts less than about 1% by weight up toabout 50% by weight, and especially less than about 1% by weight up toabout 15% by weight. In one embodiment, the secondary amines are presentin minor amounts, e.g., less than about 1%. These alkylene oxide adductshave from 2 to about 5 carbon atoms, and especially from 2 to about 3carbon atoms, the adduct also having anywhere from about 2 to about 25moles of alkylene oxide, especially from about 3 to about 20 moles ofalkylene oxide. These organic compounds reduce viscosity and improveprocessability and storage stability.

Specific abietyl amine organic compounds employed according to theinvention comprise Polyrad® 0515 (Hercules, Incorporated), ethoxylated(5 moles) dehydroabietylamine with about 15% dehydroabietyl amine,Polyrad® 1110, ethoxylated (11 moles) dehydrohydroabietylamine withabout 10% dehydroabietyl amine, including both primary and scondaryamines, and combinations thereof.

A styrenated resorcinol formaldehyde epoxy polymer employed according tothe invention comprise Penacolite® CRL-411 resin,2,2′-bis(3-[3-(3-hydroxyphenoxy)-2-hydroxy-propoxy]phenyl)propane, areaction product of resorcinol, formaldehyde, styrene and Bisphenol Adiglycidylether polymer, supplied by Indspec Chemical Corp, also knownas 2,2′-bis[3-(3-(3-hydroxyphenoxy)-2-hydroxy-propoxy]-phenyl)propanereaction product with styrene. The styrene attaches to one or bothhydroxyphenoxy groups by an addition reaction to form an ethylidenephenyl moiety or ethylene phenyl moiety on the group.

Ester hydroxyl compounds containing hydroxyl, ester and optionally ethergroups or an ester diol employed according to the invention comprisebenzoic acid, hydroxy-3-{(1-oxoneodecyl)oxy}propyl ester (EXX-RD 85 fromExxon Chemical Co) and combinations thereof. Both the styrenatedresorcinol formaldehyde epoxy polymer and ester hydroxyl compound reduceviscosity and improve processability and storage stability.

Other ester hydroxyl compounds containing hydroxyl, ester and optionallyether groups that may be employed according to the invention especiallycomprise ester diols such as propanoic acid, 3-hydroxy-2,2-dimethyl-,3-hydroxy-2,2-dimethylpropyl ester (Chemical Abstracts Registry No.1115-20-4), and the art known derivatives thereof as given in ChemicalAbstracts and incorporated herein by reference, decanedioic acid,polymer with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol and3-hydroxy-2,2-dimethylpropyl, 3-hydroxy-2,2-dimethylpropanoate (ChemicalAbstracts Registry No. 193749-51-8), also known as Ester Diol204-sebacic acid-trimethylolpropane copolymer having the molecularformula (C₁₀H₂₀O₄.C₁₀H₁₈O₄.C₆H₁₄O₃)_(x) where x equal from about 2 toabout 1000 especially from about 4 to about 750; propanoic acid,3-hydroxy-2,2-dimethyl-, 3-hydroxy-2,2-dimethylpropyl-ester, polymerwith hexahydro-1,3-isobenzofurandione andhexahydromethyl-1,3-isobenzofurandione (Chemical Abstract Registry No.228545-55-9), also known as Ester Diol 204-hexahydrophthalicanhydride-methylhexahydrophthalic anhydride copolymer, molecular formula(C₁₀H₂₀O₄.C₉H₁₂O₃.C₈H₁₀O₃)_(x) where x equal from about 2 to about 1000,and especially from about 4 to about 750; propanoic acid,3-hydroxy-2,2-dimethyl-, 3-hydroxy-2,2-dimethylpropyl ester, polymerwith 2-ethyl-2-(hydroxymethyl)-1,3-propanediol andhexahydromethyl-1,3-isobenzofurandione (Chemical Abstract Registry No.173196-70-8), molecular formula (C₁₀H₂₀O₄.C₉H₁₂O₃.C₆H₁₄O₃)_(x) where xequal from about 2 to about 1000 and especially from about 4 to about750.

The silica containing rubber compositions have from about 0.1 to about30 phr or preferably from about 0.5 to about 6 phr of the organiccompounds.

The term “rubber” comprises any natural or synthetic rubber or variousblends, especially those suitable for tires, such as the rubbers listedin U.S. Pat. Nos. 5,219,944; 5,504,137; 5,162,409; 5,665,812; 5,396,940;5,489,628; 5,905,112; 4,519,430; 5,885,389; 5,886,086; 3,873,489;5,227,425; 5,063,268 and European Patent Application No. EP 0780429A1.

The organic compounds combined with, mixed, or compounded with anynatural and/or synthetic rubber or various blends of rubber. The term“natural rubber” means rubber obtained from plant sources, such as Heveabraziliensis and Guayule, or their chemical equivalents, such assynthetic cis-1,4-polylsoprene (IR) and derivatives such as epoxidizedor methacrylate grafted rubber. The term “synthetic rubber” means anyrubber produced synthetically, via emulsion, solution or bulk or a gasphase process, such as polybutadiene (BR), chlorobutadiene rubber,epichlorohydrin rubber, polylsoprene, styrene/butadiene copolymers(SBR), styrene/isoprene/butadiene (SIBR) terpolymers, para or orthomethylstyrene/isoprene/butadiene rubber, para or orthomethylstyrene/butadiene rubber, butadiene/acrylonitrile copolymers,isoprene/acrylonitrile copolymers, ethylene/propylene/diene rubber(EPDM), butyl rubber isobutylene-isoprene copolymer and its halogenatedderivatives, brominated para-methyl styrene isobutylene rubber,butadiene/styrene/acrylonitrile terpolymers,isoprene/butadiene/acrylonitrile terpolymers, isoprene/butadienecopolymers, butadiene-alkyl acrylate or methacrylate copolymer,styrene/butadiene/alkylacrylate or alkylmethacrylate rubbers, SBR, SIBR,BR rubbers modified with silica or carbon black reactive compounds andcombinations of the aforementioned rubbers with each other and/or withnatural rubber. Blends of rubbers are preferred in some embodiments.

The organic compounds of the invention are combined, i.e., blended ormixed, with conventional tire composition ingredients and additives,known to those skilled in the art, comprising rubbers, processing aids,antioxidants, antiozonants, fillers, aromatic oils, hydrogenatedaromatic oils, naphthenic oils, waxes, silica coupling systems, adhesionpromoters, resins, coupling systems for silica (as described in EuropeanPatent Application EP 0780429A1; U.S. Pat. Nos. 4,229,333; 3,873,489;5,504,137; 5,162,409; M. P. Wagner, Rubber Chemistry and Technology, 49,p.703-773, 1976; R. J. Pickwell, Rubber Chemistry and Technology, 56,p.94-104, 1983), crosslinking systems or curing systems and combinationsthereof. Processing aids include, but are not limited to plasticizers,tackifiers, extenders, chemical conditioners, homogenizing agents, andpeptizers such as mercaptans, synthetic oils, petroleum and vegetableoils, paraffin oils, hydrogenated aromatic oils, resins, rosins and thelike and combinations thereof. Accelerators but are not limited toinclude guanidines, thioureas, thiurams, sulfenamides, thiocarbamates,amines, xanthates, thiazoles and the like and combinations thereof.Crosslinking systems or curing systems include peroxides, sulfur, sulfurdonors, accelerators, zinc oxides and fatty acids and combinationsthereof. Fillers include but are not limited to reinforcing and/orconductive carbon black, clay, silica, bentonite, titanium dioxide,talc, calcium carbonate, calcium sulfate, silicates, starch and shortvegetable or synthetic fibers or pulp, and the like, and combinationsthereof.

Compositions of the invention are typically combined, i.e., blended, ormixed with one another using conventional rubber compounding apparatus,in a single step or in multiple steps in a batch or continuous internalmixer, such as a Banbury, Intermesh mixer single-screw extruder, counteror corotating twin screw extruder or on a two-roll mill until ahomogeneous blend is obtained.

Referring to FIG. 1, rubber compositions of this invention can be usedin the construction of various components of a tire, e.g., in tiretreads 20 and/or sidewalls 65, bead fillers 60, components of the beadarea, including the bead composition 55, tread cushion 21, belt 30,inner liner 40, overlay 42, and carcass 50 of a tire. Disposedcrown-wise to the tire carcass 50, in the usual manner, is a treadcomponent or band 20, and inserted between the carcass and the treadband or tread cushion is a belt structure 30 and above the belt anoptional overlay component, above which lies a tread cushion 42 cappedby the tread 20. The belt comprises two radially superimposed layers, 31and 32, of cords disposed at angles with respect to the midcircumferential plane of the tire in opposite directions, preferablysymmetrically. Extending from tread portion 20 toward bead area 55 onthe tire exterior is the sidewall 65, which may comprise the same rubbercomposition as the tread portion 20 or preferably a different rubbercomposition.

The following examples are presented to further illustrate and explainthe present invention. Unless otherwise mentioned, all parts andpercentages are by weight. All physical and mechanical measurements wereconducted using industry standard test methods or special methods asindicated.

EXAMPLES

Rubber compositions containing the materials listed in Tables 1, 3, 5,7, 9, 11, 13 and 16 were combined, i.e., mixed in a BrabenderPlasticorder (420 ml) mounted with cam rotors by using a fill factor of0.7, a rotor velocity of 75 rpm (drive to drive ratio, 3:2) and astarting temperature of 100° C. After mixing, the compounds weremasticated at room temperature on a two-roll mill (22-24° C.) for 7minutes. The curatives (CBS, DPG80, sulfur) as noted were added on mill,when necessary. The mixing sequence is shown here below and is the samefor all of the compounds studied:

MIXING TIME (in min.) INGREDIENTS ADDED 0 polymer 2 silica + allingredients except 6 PPD 5.5 6PPD 6.5 end Starting mixing temperature100° C. Total mixing time 2.5 above 150° C. (min.) Final temperature165-167° C.

In all of the cases listed in Tables 1, 3, 5, 7, 9, 11, 13, 16, solutionSBR is styrene butadiene rubber with 25% styrene and 55% vinyl; silicais precipitated silicon dioxide (VN3 from Degussa Corp.); carbon blackis Vulcan 1380 from Cabot Corp.; 6PPD isN-1,3dimethylbutyl-N′-p-phenylenediamine; X50S is a 50% dispersion of3,3′-bis(triethoxysilylpropyl)tetrasulfide (TESPT) in N330 carbon black;wax is microcrystalline wax; aromatic oil is Sundex 8125 from Sun OilCo.; DPG80 is 80% diphenylguanidine dispersed on an inert carrier; CBSis N-cyclohexylbenzothiazolesulfenamide; all amounts are in parts byweight per hundred parts of rubber.

Tables 2, 4, 6, 8, 10, 12, 14, 17 list the cure characteristics, tensileproperties of the vulcanizate and processability of the uncuredcompositions whose compositions are shown in Tables 1, 3, 5, 7, 9, 11,13, 16. Table 15 only lists the processability characteristics ofuncured compositions with and without curing ingredients (sulfur, CBS,DPG80). The curing behavior of the compounds was measured at 160° C. byusing a Monsanto Rheometer 100 with an arc angle of 3° (ASTM D2084). Amarching cure was observed in all cases. For measuring physicalproperties of the compositions, a cure time of 60 minutes was employedfor silica and silica/carbon black filled compositions, and a cure timeof 40 minutes was employed for carbon black filled compositions. A moldlag time of 5 minutes was added in all cases to the cure time. Becauseof the marching cure, i.e., “t₉₀” or optimum cure is defined as the timeneeded for the measured torque of a modified composition (with epoxycompounds, and the like as the additive) to reach the value of that of acontrol recipe (without any organic compound) after 60 minutes for asilica-filled composition, and after 40 minutes for a carbonblack-filled composition. Five minutes were added to the obtained valuefor mold lag.

Processability is defined inversely as the roughness of the surface ofthe extrudate after an extrusion experiment. The extrudate is defined asthe product of an extrusion experiment. The processability was evaluatedby the measure of the peak stress during a slow start-up flow experimentperformed by using a modified multi speed Mooney viscometer equippedwith a grooved biconical rotor, at a rotor rotation speed of 0.1 rpm at120° C. after a preheating period of 10 minutes (S. Schaal and A. Y.Coran, Paper No. 46, presented at a meeting of the Rubber Division,American Chemical Society, Orlando, Fla., Sep. 21-24, 1999). The higherthe maximum stress, which is called Mooney peak, the poorer theprocessability, i.e., the greater the roughness of the extrudate afteran extrusion experiment. Processability, as defined here, is measuredafter a storage period of 8 days at 70° C. The processability index (PI)is defined as the ratio of the height of the Mooney peak of the modifiedcomposition to the height of the Mooney peak exhibited by the controlcomposition. The lower the value of PI, the more improvement inprocessability compared to the control composition. Unless specified,all the processability measurements were made on non-productivecompositions, i.e., compositions that do not contain any curingingredients (CBS, DPG80, sulfur).

In order to evaluate the effect of the additives on the mechanicalproperties measured in tension, each modified composition, i.e.,containing an additive, was then compression molded in a 2 mm-thick moldunder 24 MPa at 160° C. for a period equal to t₉₀ plus 5 minutes. Asmentioned above, the cure time for a control recipe, i.e., withoutadditive, was arbitrarily set at 65 minutes. In some cited cases, allthe specimens were cured for 60 minutes at 160° C. in the case ofsilica-filled compositions and 45 minutes in the case of carbon blackfilled compositions. Dumbbell shape specimens (ASTM D412, die type C)were cut from the 2 mm-thick sheet obtained after curing. The tensiletest was performed at room temperature at a crosshead speed of 500mm/min on the cured composition. Ultimate strength, ultimate strain,modulus at 100% strain (M100), modulus at 300% strain (M300) wererecorded. The ratio M300/M100 was calculated as a measure of the fillerdispersion quality (Cf. Rauline, U.S. Pat. No. 5,227,425). The higherthe M300/M100 ratio, the better the dispersion of the filler particlesin the rubber matrix.

Example 1

A silica reinforced rubber composition was used for the evaluation ofthe effect of epoxy-containing organic compounds on the curecharacteristics and the tensile properties of the vulcanizate as well ason the processability of the uncured compositions. Table 1 gives thecompositions. The properties mentioned above are reported in Table 2.SS01 represents the control composition. The addition ofN,N-diglycidylaniline (SS02) provides a substantial decrease in curingtime compared to the control composition. The Mooney peak and theprocessability index of SS02 are much lower than that of SS01. Thisindicates that the addition of N,N-diglycidylaniline to the controlcomposition leads to a significant improvement of the resistance toadverse rheological changes that occur during storage. It can also beseen than N,N-diglycidylaniline (SS02) is much more effective than lowmolecular weight glycols such as di(ethyleneglycol)diethylether (SS03)or di(ethyleneglycol)ethylether acetate (SS04) for processability afterstorage.

TABLE 1 Formulations SS01 SS02 SS03 SS04 solution SBR 100 100 100 100silica 60 60 60 60 X50S 9.6 9.6 9.6 9.6 stearic acid 3 3 3 3 zinc oxide2 2 2 2 6PPD 1.5 1.5 1.5 1.5 wax 1 1 1 1 aromatic oil 12 12 12 12N,N-diglycidylaniline — 2 — — Di(ethyleneglycol)diethylether* — — 2 —Di(ethyleneglycol)ethylether — — — 2 acetate* Curing system: sulfur 1.21.2 1.2 1.2 CBS 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.25 *These twoglycols were used as reference for comparison, Cf., M. P. Wagner, RubberChemistry and Technology, 49, 703, 1976

TABLE 2 Cure, Physical and Processing Properties SS01 SS02 SS03 SS04Cure characteristics (ASTMD2084) t₂ (min.) 6.5 6.7 6.9 6.4 cure time(min.) 65 52 58 51 Tensile properties (ASTM D412) Elongation at break(%) 356.25 342.20 346.62 353.42 Stress at break (MPa) 19.53 18.42 18.1418.67 M100 (MPa) 3.49 3.71 3.46 3.40 M300 (MPa) 15.65 15.64 15.04 15.08M300/M100 4.48 4.22 4.35 4.44 Processability Mooney peak (kPa) 119.069.5 104.0 115.0 processability index 1.00 0.58 0.87 0.97

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 2

In this example, the compositions and their properties are shown inTable 3 and Table 4 respectively. SS05 is the control composition with asilane coupling system (TESPT). SS08 is a composition without a silanecoupling system (TESPT). It can be seen that the presence of thecoupling system significantly improves the cure rate and the mechanicalproperties and especially, the M300/M100 ratio, which is a measure ofthe quality of the dispersion of the filler in the matrix (cf. RaulineU.S. Pat. No. 5,227,425). The processability index, however, is notsignificantly affected. By comparing the properties of SS06 and SS07 tothose of SS05, it can be concluded that the addition ofN,N-diglycidyl-4-glycidyloxyaniline and ethoxylated hydroabietyl amineto the control composition (with coupling system, e.g., TESPT), not onlyimprove the cure rate significantly, i.e., reduced cure time, but alsolead to a significant improvement of the storage stability especially inthe case of N,N-diglycidyl-4-glycidyloxyaniline. By comparing theproperties of SS08 and SS09, it can be concluded that the addition ofpolypropylene glycol diglycidylether to a control recipe that does notcontain any silane coupling system unexpectedly decreases the value ofthe processability index; this may suggest the occurrence of a chemicalreaction between the silica surface silanols with the epoxy moiety ofthe organic compound.

TABLE 3 Formulations SS05 SS06 SS07 SS08 SS09 solution SBR 100 100 100100 100 silica 60 60 60 60 60 TESPT (X50S) 9.6 9.6 9.6 — — stearic acid3 3 3 3 3 zinc oxide 2 2 2 2 2 6PPD 1.5 1.5 1.5 1.5 1.5 wax 1 1 1 1 1aromatic oil 12 12 12 12 12 N,N-diglycidyl-4- — 2 — — —glycidyloxyaniline Ethoxylated dehydro- — — 2 — — abietyl amine^(a)Mixture Polypropyleneglycol- — — — — 2 diglycidylether Curing system:sulfur 1.2 1.2 1.2 1.2 1.2 CBS 1.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.251.25 1.25 ^(a)Polyrad ® 0515 from Hercules Incorporated, a mixture of 85parts of 5 moles ethoxylated dehydroabietyl amine and 15 parts ofdehydroabietyl amine. The polypropyleneglycoldiglycidyl ether in thisand all other examples had a formula weight of 304.

TABLE 4 Cure, Physical and Processing Properties SS05 SS06 SS07 SS08SS09 Cure characteristics (ASTM D2084) t₂ (min.) 6.5 5.2 6.6 6.5 10.6cure time (min.) 65 53 50 145*   173*   Tensile properties (ASTM D412)Elongation at break (%) 364.47 356.43 362.89 549.05 595.92 Stress atbreak (MPa) 18.49 19.71 19.41 15.94 13.64 M100 (MPa) 3.18 3.78 3.63 2.731.84 M300 (MPa) 14.15 16.05 15.35 6.54 4.59 M300/M100 4.45 4.25 4.232.40 2.50 Processability Mooney peak (kPa) 103.0 61.5 98.6 111.0 50.9processability index 1.00 0.60 0.96 1.08 0.49 *numbers obtained fromextrapolation by assuming a 1^(st) order reaction after 60 minutes ofcure

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 3

In this example, the compositions and their properties are shown inTable 5 and Table 6 respectively. SS10 is the control composition.Epoxidized soybean oil (SS11) and 25 mol per cent epoxidized naturalrubber (ENR25) at low levels (SS12) both reduce the cure rate whilelowering the processability index in a silica-filled composition. Table6 shows that low molecular weight epoxy compounds such asdiglycidyl-1,2-cyclohexanedicarboxylate (SS13) andexo-2,3-epoxynorbornane (SS15) both increase the cure rate and reducethe value of the processability index even further than do eitherepoxidized soybean oil or ENR25. This shows that the use oflow-molecular-weight epoxy compounds according to the invention providesunexpected superior resistance to unfavorable rheological changes thatoccur during storage in the case of silica-filled rubber compositions,when compared to epoxidized soybean oil and ENR25 as illustrated bySegatta et al, U.S. Pat. No. 5,396,940; and Sandstrom, U.S. Pat. No.5,489,628. It should be noted that no beneficial effect on viscosity ofepoxidized soybean oil is observed when carbon black is the predominantfiller as shown by Stevens et al., DE 19700967 A1.

TABLE 5 Formulations SS10 SS11 SS12 SS13 SS14 SS15 solution SBR 100 100100 100 100 100 silica 60 60 60 60 60 60 X50S 9.6 9.6 9.6 9.6 9.6 9.6stearic acid 3 3 3 3 3 3 zinc oxide 2 2 2 2 2 2 6PPD 1.5 1.5 1.5 1.5 1.51.5 wax 1 1 1 1 1 1 aromatic oil 12 12 12 12 12 12 Epoxidized — 2 — — —— soybean oil ENR 25 — — 2 — — — Diglycidyl-1,2- — — — 2 — — cyclohexanedicarboxylate (2,3-epoxy- — — — — 2 — propyl)benzene exo-2,3-epoxy- — —— — — 2 norbornane Curing system: sulfur 1.2 1.2 1.2 1.2 1.2 1.2 CBS 1.81.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.25 1.25 1.25

TABLE 6 Cure, Physical and Processing Properties SS10 SS11 SS12 SS13SS14 SS15 Cure char- acteristics (ASTM D2084) t₂ (min.) 6.0 6.9 6.2 6.37.0 6.8 cure time 60 60 60 60 60 60 (min.) t₉₀ (min.) 65 92 68 44 88 53Tensile properties (ASTM D412) Elongation at 340.2 416.8 348.6 341.6371.7 341.8 break (%) Stress at 18.10 19.10 16.90 18.55 17.66 17.92break (MPa) 3.26 2.67 3.11 3.58 3.09 3.44 M100 (MPa) M300 (MPa) 14.8711.79 13.80 15.64 13.14 15.02 M300/M100 4.56 4.42 4.44 4.37 4.25 4.37Processability Mooney peak 120.0 85.8 85.0 57.3 68.1 65.3 (kPa)processability 1.00 0.72 0.71 0.48 0.57 0.54 index

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 4

In this example, the compositions and their properties are shown inTable 7 and Table 8 respectively. SS16 is the control composition. Table8 shows that all of the organic compounds mentioned below reduce thecure time and improve the processability, after storage, of silicafilled rubber compositions: poly(Bisphenol A-co-epichlorhydrin) glycidylend-capped, MW=380, poly(Bisphenol A-co-epichlorhydrin) glycidylend-capped, MW=6100, glycidylbutyrate, Penacolite® CRL-411 resin(reaction product of resorcinol, formaldehyde, styrene and Bisphenol Adiglycidylether polymer, Indspec Chemical Corp.), an ester diol(EXXRD-85 from Exxon Chemical Co.), and glycidylneodecanoate.

TABLE 7 Formulations SS16 SS17 SS18 SS19 SS20 SS21 SS22 solution SBR 100100 100 100 100 100 100 silica 60 60 60 60 60 60 60 X50S 9.6 9.6 9.6 9.69.6 9.6 9.6 stearic acid 3 3 3 3 3 3 3 zinc oxide 2 2 2 2 2 2 2 6PPD 1.51.5 1.5 1.5 1.5 1.5 1.5 wax 1 1 1 1 1 1 1 aromatic oil 12 12 12 12 12 1212 Poly(Bisphenol A-co- — 2 — — — — — epichlorhydrin) glycidylend-capped, MW = 380 Poly(Bisphenol A-co- — — 2 — — — — epichlorhydrin)glycidyl end-capped, MW = 6100 Glycidylbutyrate — — — 2 — — —Penacolite ™ CRL-411^(a) — — — — 2 — Ester diol^(b) — — — — — 2 —Glycidylneodecanoate — — — — — — 2 Curing system: sulfur 1.2 1.2 1.2 1.21.2 1.2 1.2 CBS 1.8 1.8 1.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.251.25 1.25 1.25 ^(a)reaction product of resorcinol, formaldehyde andBisphenol A diglycidylether polymer and styrene from Indspec ChemicalCorp. ^(b)reactive diluent EXXRD-85, i.e., benzoic acid, 4 hydroxy-3-{(1-oxoneodecyl)oxy}propyl ester (85% active) from Exxon Chemical

TABLE 8 Cure, Physical and Processing Properties SS16 SS17 SS18 SS19SS20 SS21 SS22 Cure characteristics (ASTM D2084) t₂ (min.) 6.8 6.7 7.06.8 7.0 6.7 6.9 cure time (min.) 65 55 46 38 53 40 50 Tensile properties(ASTM D412) Elongation at break (%) 479.3 502.7 482.1 461.9 440.1 469.7461.5 Stress at break (MPa) 19.37 18.33 17.00 19.16 17.45 17.96 19.02M100 (MPa) 2.17 2.05 2.24 2.43 2.48 2.25 2.31 M300 (MPa) 8.92 8.34 8.5610.49 10.07 9.42 10.24 M300/M100 4.12 4.06 3.81 4.33 4.06 4.19 4.43Processability Mooney peak (kPa) 121.0 74.4 87.3 52.3 95.1 93.7 69.5processability index 1.00 0.61 0.72 0.43 0.79 0.77 0.57

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 5

In this example, the compositions and their properties are shown inTable 9 and Table 10 respectively. SS23 is the control composition. Itcan be seen from Table 10, that the use of diethyleneglycol (SS24) (M.P. Wagner, Rubber Chemistry and Technology, 49, 703, 1976) andexo-2,3-epoxynorbornane (SS26) significantly reduces the cure time aswell as the value of the processability index compared to the controlcomposition. The use of glycidyl-4-methoxyphenylether (SS25) alsoreduces the value of the processability index compared to the controlcomposition.

TABLE 9 Formulations SS23 SS24 SS25 SS26 SS27 solution SBR 100 100 100100 100 silica 60 60 60 60 60 X50S 9.6 9.6 9.6 9.6 9.6 stearic acid 3 33 3 3 zinc oxide 2 2 2 2 2 6PPD 1.5 1.5 1.5 1.5 1.5 wax 1 1 1 1 1aromatic oil 12 12 12 12 12 Diethyleneglycol* — 2 — — — Glycidyl-4- — —2 — — methoxyphenylether exo-2,3-epoxynorbornane — — — 2 —Polypropyleneglycol — — — — 2 diglycidylether Curing system: sulfur 1.21.2 1.2 1.2 1.2 CBS 1.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.25 1.25*Cf., M. P. Wagner, Rubber Chemistry and Technology, 49, 703, 1976.

TABLE 10 Cure, Physical and Processing Properties SS23 SS24 SS25 SS26SS27 Cure characteristics (ASTM D2084) t₂ (min.) 6.9 6.7 6.6 7.0 6.2cure time (min.) 65 39 69 55 51 Tensile properties (ASTM D412)Elongation at break (%) 348.9 377.0 348.1 344.5 368.2 Stress at break(MPa) 18.21 19.48 18.48 17.37 19.06 M100 (MPa) 3.26 3.24 3.50 3.31 3.38M300 (MPa) 14.79 14.30 15.20 14.48 14.69 M300/M100 4.52 4.36 4.38 4.294.30 Processability Mooney peak (kPa) 103.0 49.4 70.5 81.4 64.7processability index 1.00 0.48 0.68 0.79 0.63

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 6

In this example, the compositions and their properties are shown inTable 11 and Table 12 respectively. SS28 is the control composition. Itcan be seen from Table 12, that the use ofpoly(phenylglycidylether)-co-formaldehyde (SS31), poly(BisphenolA-co-epichlorhydrin) glycidyl end-capped, MW=380 (SS32), poly(BisphenolA-co-epichlorhydrin) glycidyl end-capped, MW=6100 (SS33) andpolyethyleneglycol, MW=1000 (SS34) significantly reduce the cure time aswell as the value of the processability index compared to the controlcomposition. The use of 2-ethylhexylglycidylether (SS29) significantlyreduces the value of the processability index compared to the controlcomposition. It should be noted that the use of a lower molecular weightepoxy resin (SS32) provides better storage stability than a highermolecular weight epoxy resin (SS33). In addition, it is clear from Table12, that low molecular weight epoxy compounds (SS29, SS30, SS31) aremore effective than polyethyleneglycol (M. P. Wagner, Rubber Chemistryand Technology, 49, 703, 1976) (SS34) as far as slowing down the adverserheological changes that occur during storage.

TABLE 11 Formulations SS28 SS29 SS30 SS31 SS32 SS33 SS34 solution SBR100 100 100 100 100 100 100 silica 60 60 60 60 60 60 60 X50S 9.6 9.6 9.69.6 9.6 9.6 9.6 stearic acid 3 3 3 3 3 3 3 zinc oxide 2 2 2 2 2 2 2 6PPD1.5 1.5 1.5 1.5 1.5 1.5 1.5 wax 1 1 1 1 1 1 1 aromatic oil 12 12 12 1212 12 12 2-ethylhexylglycidylether — 2 — — — — — Polypropyleneglycol — —2 — — — — diglycidylether Poly(phenylglycidylether)- — — — 2 — — —co-formaldehyde Poly(Bisphenol A-co- — — — — 2 — — epichlorhydrin)glycidyl end-capped, MW = 380 Poly(Bisphenol A-co- — — — — — 2 —epichlorhydrin) glycidyl end-capped, MW = 6100 Polyethyleneglycol,* — —— — — — 2 MW = 1000 Curing system: sulfur 1.2 1.2 1.2 1.2 1.2 1.2 1.2CBS 1.8 1.8 1.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.25 1.25 1.25 1.25*Cf., M.P. Wagner, Rubber Chemistry and Technology Vol. 49, 703, 1976

TABLE 12 Cure, Physical and Processing Properties SS28 SS29 SS30 SS31SS32 SS33 SS34 Cure characteristics (ASTM D2084) t₂ (min.) 6.8 7.4 7.57.2 7.5 7.5 6.8 cure time (min.) 60 60 60 60 60 60 60 t₉₀ (min.) 65 8763 60 59 59 40 Tensile properties (ASTM D412) Elongation at break (%)340.1 374.3 357.9 343.5 345.8 364.8 331.5 Stress at break (MPa) 17.1617.32 18.55 17.17 18.10 18.81 17.90 M100 (MPa) 3.06 2.74 3.21 3.40 3.513.58 3.58 M300 (MPa) 14.26 12.64 14.70 14.47 15.10 14.68 15.71 M300/M1004.66 4.61 4.58 4.26 4.30 4.10 4.39 Processability Mooney peak (kPa)107.0 53.6 48.9 56.1 74.4 87.3 67.4 processability index 1.00 0.50 0.460.52 0.70 0.82 0.63

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 7

In this example, the compositions and their properties are shown inTable 13 and Table 14 respectively. SS35 is the control composition forthe silica-carbon black filled composition. SS38 is the controlcomposition for the carbon black composition. Table 14 shows that theuse of polypropyleneglycoldiglycidylether (SS37) in a rubber compositionfilled with both silica and carbon black reduces the cure time andimproves the processability after storage.

TABLE 13 Formulations SS35 SS36 SS37 SS38 SS39 SS40 solution SBR 100 100100 100 100 100 silica 30 30 30 — — — carbon black 30 30 30 60 60 60X50S 4.8 4.8 4.8 — — — stearic acid 3 3 3 3 3 3 zinc oxide 2 2 2 2 2 26PPD 1.5 1.5 1.5 1.5 1.5 1.5 wax 1 1 1 1 1 1 aromatic oil 11 11 11 10 1010 2-ethylhexyl- — 2 — — 2 — glycidylether Polypropyl- — — 2 — — 2eneglycol diglycidylether Curing system: sulfur 1.2 1.2 1.2 1.2 1.2 1.2CBS 1.8 1.8 1.8 1.8 1.8 1.8 DPG80 1.25 1.25 1.25 1.25 1.25 1.25

TABLE 14 Cure, Physical and Processing Properties SS35 SS36 SS37 SS38SS39 SS40 Cure char- acteristics (ASTM D2084) t₂ (min.) 4.0 4.5 4.2 3.94.5 4.0 cure time 65 120 63 45 45 45 (min.) t₉₀ (min.) 60 115 58 45 180150 Tensile properties (ASTM D412) Elongation 365.01 320.96 357.02362.38 477.41 446.68 at break (%) Stress at 20.70 18.94 19.83 16.7613.20 15.77 break (MPa) M100 (MPa) 3.98 3.88 3.89 3.58 2.35 2.82 M300(MPa) 16.94 17.58 16.56 14.02 8.29 10.69 M300/M100 4.26 4.53 4.26 3.913.53 3.79 Processability Mooney peak 95.1 73.4 73.3 35.2 31.7 33.1 (kPa)processability 1.00 0.77 0.77 1.00 0.90 0.94 index

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

Example 8

This example shows the compositions and their properties in Table 9 andTable 15 respectively, and the effect of the curing system (CBS, DPG80,sulfur) on the processability, evaluated in conjunction with an epoxyadditive, i.e., polypropyleneglycoldiglycidylether. Table 15 shows thatthe curing system somewhat improves the processability after storage ofa silica-filled rubber composition (compare SS23 (non productive) andSS24 (productive)). It is also seen that the use of epoxy additives,i.e., in this case, polypropyleneglycoldiglycidylether, in conjunctionwith the curing system, further improves the processability afterstorage (compare SS23 (productive) and SS27 (productive)). Theseexamples show that the results obtained for the previous examplesrelative to non-productive silica-filled rubber composition are alsovalid for silica-filled rubber compositions containing curatives(productive).

TABLE 15 Processing Properties SS23 SS27 (non- SS23 (non- SS27productive) (productive) productive) (productive) Processability Mooneypeak 117.0 103.0 82.2 75.8 (kpa) processability 1.00 0.88 0.70 0.65index

The effect of the curing system (CBS, DPG80, sulfur) on processabilitywas evaluated. In this particular case, processability was measuredafter a storage period of 31 days at 40° C. The storage temperature waslowered compared to the usual test described previously in order toprevent a premature curing of the compositions.

Example 9

This example deals with the effects of additives on the dynamicmechanical properties of silica-filled rubber vulcanizates. It was seenin the preceding examples that the use of certain epoxy compounds insilica-filled rubber compositions both improve their processabilityafter storage and reduces their cure time. FIG. 2 shows the effect ofadditives on tan δ measured at 1 Hz and 0.1% strain as a function oftemperature for silica-filled rubber vulcanizates. FIG. 3 shows theeffect of additives on G′ measured at 1 Hz and 0.1% strain as a functionof temperature for silica-filled rubber vulcanizates. No majordifferences are observed between the viscoelastic properties of thedifferent vulcanizates tested. The presence of these additives does notsignificantly affect the dynamic mechanical properties of silica-filledrubber vulcanizates, while improving their processability (afterstorage), as well as in some cases, their cure rates.

Example 10

A silica reinforced rubber composition was used for the evaluation ofthe effect of epoxy-containing compositions on the cure characteristicsand the tensile properties of the vulcanizate as well as on theprocessability of the uncured compositions. Table 16 gives thecompositions. The properties mentioned above are reported in Table 17.SS41 represents the control composition. The Mooney peak and theprocessability index of SS42 are much lower than that of SS41. Thisindicates that the addition of isopropylglycidylether to the controlcomposition leads to a significant improvement of the resistance toadverse rheological changes that occur during storage, whereas the cycloepoxy, where the epoxy group is located on a cyclohexyl ring is noteffective in improving processability. Note that the values of theMooney Peak are much higher in this example than in the previousexamples. This is due to the fact that a different batch of SSBR (ofhigher polydispersity) was used for the experiments conducted in thepresent example. The dump temperature was 10° C. higher for theseexperiments compared to the previous examples. However, thebatch-to-batch variations are negligible when considering theprocessability index of compositions made at a constant dumptemperature.

TABLE 16 Formulations SS41 SS42 SS43 solution SBR 100 100 100 silica 6060 60 X50S 9.6 9.6 9.6 stearic acid 3 3 3 zinc oxide 2 2 2 6PPD 1.5 1.51.5 wax 1 1 1 aromatic oil 12 12 12 Isopropylglycidylether — 2 —Cycloepoxy^(c) — — 2 Curing system: sulfur 1.2 1.2 1.2 CBS 1.8 1.8 1.8DPG80 1.25 1.25 1.25^(c)3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate

TABLE 17 Cure, Physical and Processing Properties SS41 SS42 SS43 Curecharacteristics (ASTM D2084) t₂ (min.) 6.8 6.2 5.7 cure time (min.) 6572 45 Tensile properties (ASTM D412) Elongation at break (%) 351.4 340.5368.8 Stress at break (MPa) 19.30 17.63 20.30 M100 (MPa) 2.97 3.09 3.33M300 (MPa) 14.66 14.75 15.66 M300/M100 4.98 4.77 4.70 ProcessabilityMooney peak (kPa) 169.0 140.3 172.4 processability index 1.00 0.83 1.02

Processability was measured on non productive recipes, i.e., without thecuring system. The curing system was added on a room-temperaturetwo-roll mill for the evaluation of the curing characteristics.

As noted in the specification, the invention involves combining variousorganic compounds with a rubber compound or rubber composition whichincludes not only the physical mixing of the various compounds orcompositions which, for the most part comprise solid materials at roomtemperature and elevated temperatures (<300° C.) that occur duringmixing, but also mixing the various organic compounds and rubbercompounds or compositions where one or both are in the liquid phase.This liquid phase includes, not only melted organic compounds andviscous fluid rubber compounds or compositions at elevated temperatures,but also fluid dispersions of the organic compounds and/or the rubbercompounds or compositions.

The rubber compounds comprise the various rubbers set forth in thespecification whereas the rubber compositions comprise these rubbers incombination with fillers, primarily silica and the other fillers notedherein and rubber additives also noted herein. In some instances, thesupplier of the rubber compound will add conventional rubber additivesto the rubber. In any event, the process of the invention involvescombining a mixture comprising rubber, silica and at least one of theaforementioned low molecular weight organic compounds by which it ismeant that either the rubber or the rubber in combination with silicaand in some instances other fillers and additives are combined with thelow molecular weight organic compound.

Combining the organic compounds with the rubber compound or rubbercomposition and/or silica involves mixing the solid and/or liquid phasematerials in a high shear mixer such as a Banbury mixer, Intermeshmixer, Extruder mixer, Sigma blade mixer, 2-roll rubber mill and similarapparatus known in the rubber compounding art.

During the combination or mixing of the organic compounds with therubber compound or composition, chemical reactions can occur between thevarious components such as reactions of the organic compounds withhydroxyl or other reactive groups on the surface of the silica or otherfiller in the rubber composition, or the reaction of the crosslinking orcuring system with the rubber compound or composition, and in someinstances with the organic compounds during the curing of the mixture asdescribed herein. Accordingly, the invention comprises not only theprocess of combining the various organic compounds with the rubbercompound or composition and other components, but also the productobtained by the process at all stages of the process, whether thecomposition made according to the process of the invention includes orexcludes a curing system, and whether or not the product made by theprocess of the invention is subsequently subjected to a curing reactionwith a crosslinking or curing system.

The various numerical ranges describing the invention, as set forth inthe specification, also include any combination of the lower ends of theranges with the higher ends of the ranges including, inter alia, rangesof concentrations of compounds or compositions, ratios of thesecompounds or compositions to one another, molecular weights, ratios ofmonomer units or polymer blocks to one another, average number ofpolymer blocks in the in the polymer compounds of the invention, wholenumber and/or fractional number values encompassed by these ranges, aswell as ranges encompassed within these ranges.

The specification also refers to using at least one compound orcomposition, by which it is intended that either a single compound orcomposition or various combinations of the compound or composition areincluded. Additionally, the specification refers to combinations ofcompounds or compositions. In either event, the preferred combination ofcompounds or compositions includes the two component, three component orfour component combinations.

The specification sets forth various references to describe not only theprior art, but also various features of the invention. All of thesereferences are incorporated herein in their entirety.

It will be apparent to those skilled in the art that modifications andvariations can be made in the novel composition of matter and processand product produced by the process as described herein withoutdeparting from the spirit or scope of the invention. It is intended thatthese modifications and variations and their equivalents are to beincluded as part of this invention, provided they come within the scopeof the appended claims.

What is claimed is:
 1. A process for improving the processability,storage stability and/or cure rate of an uncured silica reinforcedrubber composition where silica comprises the major filler in saidreinforced rubber composition, comprising combining a mixture comprisingrubber, silica and at least one organic compound of relatively lowmolecular weight comprising, an abietyl compound, or an ester hydroxylorganic compound containing at least one hydroxyl group, at least oneester group, and optionally an ether group, where the molecular weightof said organic compound of relatively low molecular weight is less thanabout 7,000, wherein said organic compound is ethoxylated (5 moles)dehydroabietylamine in admixture with dehydroabietylamine, ethoxylated(11 moles) dehydroabietylamine in admixture with dehydroabietylamine, oran ester diol, and combinations thereof.
 2. A process according to claim1 where said ester diol is benzoic acid,4-hydroxy-3-{(1-oxoneodecyl)oxy} propyl ester.
 3. A process forimproving the processability, storage stability and/or cure rate of anuncured silica reinforced rubber composition where silica comprises themajor filler in said reinforced rubber composition, comprising combininga mixture comprising rubber, silica and at least one organic compoundcomprising an organic compound of relatively low molecular weight thatcontains at least one functional group, wherein said functional group isat least an epoxy functional group located in terminal or stericallyunhindered positions in the molecule of said organic compound, where themolecular weight of said organic compound of relatively low molecularweight is less than about 7,000 wherein the organic compound isN,N-diglycidylaniline, N,N-diglycidyl-4-glycidyl oxyaniline,polypropylene glycol diglycidyl ether,3,4-epoxycyclohexylmethyl-3,4-epoxycylcohexanecarboxylate,diglycidyl-1,2-cyclohexane dicarboxylate, 2,3-epoxypropyl benzene,exo-2,3-epoxynorbornane, poly(bisphenol A-co-epichlorohydrin) endcapped, glycidyl 4-methyloxy phenyl ether, poly(phenylglycidylether)-co-formaldehyde, cresyl glycidyl ether, diglycidyl ether of1,4-butanediol, dimer acid diglycidyl ester, 1,2-epoxy-9-decene,N-(2,3-epoxypropyl)phthalimide, glycidyl butyrate, glycidylneodecanoate, and combinations thereof.
 4. A process for improving theprocessability, and reduce the cure time of an uncured silica reinforcedrubber composition where silica comprises the major filler in saidreinforced rubber composition, comprising combining a mixture comprisingrubber, silica and at least one organic compound comprising an organiccompound of relatively low molecular weight that contains at least onefunctional group, wherein said functional group is at least an epoxyfunctional group located in terminal or sterically unhindered positionsin the molecule of said organic compound, or said organic compoundcomprises an abietyl compound, or an ester hydroxyl organic compoundcontaining at least one hydroxyl group, at least one ester group, andoptionally an ether group, where the molecular weight of said organiccompound of relatively low molecular weight is less than about 7,000wherein said organic compound is N,N-diglycidyl aniline,N,N-diglycidyl-4-glycidyl oxyaniline, polypropylene glycol diglycidylether, diglycidyl-1,2-cyclohexane dicarboxylate,exo-2,3-epoxynorbornane, poly(bisphenol A-co-epichlorohydrin) endcapped, glycidyl butyrate, glycidyl neodecanoate,poly(phenylglycidylether)-co-formaldehyde,3,4-epoxycyclohexylmethyl-3,4-epoxycylcohexanecarboxylate, ethoxylated(5 moles) dehydroabietylamine in admixture with dehydroabietylamine,ethoxylated (11 moles) dehydroabietylamine in admixture withdehydroabietylamine, or benzoic acid, 4hydroxy-3-{(1-oxoneodecyl)oxy}propyl ester, and combinations thereof. 5.A process according to one of claims 1-3 and 4 wherein said rubber isnatural rubber, epoxidized natural rubber, methacrylated natural rubber,synthetic polylsoprene, polybutadiene, styrene butadiene copolymers,styrene/isoprene/butadiene copolymers, para or orthomethylstyrene/butadiene rubbers, isoprene/butadiene copolymers, para orortho methyl styrene/butadiene/isoprene terpolymers,ethylene/propylene/diene rubbers, butyl rubber, isobutylene-isoprenecopolymer and its halogenated derivatives, brominated para-methylstyrene isobutylene rubber, butadiene/styrene/acrylonitrile terpolymers,isoprene/styrene/acrylonitrile terpolymers, butadiene/acrylonitrilecopolymers, isoprene/acrylonitrile copolymers,butadiene/isoprene/acrylonitrile terpolymers, butadiene-alkyl acrylateor methacrylate copolymers, styrene/butadiene/alkyl acrylate or alkylmethacrylate rubbers, modified styrene/butadiene or butadiene rubberswith silica or carbon black reactive functional groups, and combinationsof the aforementioned rubbers with each other and/or with naturalrubber.
 6. A process according to claim 5 wherein said rubbercomposition further includes processing aids, aromatic oils, napthenicoils, paraffin oils, rosin oils, antioxidants, antiozonants, waxes,fillers, resins, adhesions promoters, silica coupling systems,crosslinking systems or curing systems and combinations thereof.
 7. Aprocess according to claim 6 wherein said silica coupling systemscomprise polyfunctional organosilanes.
 8. The process of claim 7 whereinsaid polyfunctional organosilane comprisesbis(3-triethoxysilylpropyl)tetrasulfide.
 9. A process according to oneof claims 1-3 and 4 wherein said organic compound is present in anamount from about 0.1 to about 30 phr, and said silica is present in anamount greater than about 15 phr.
 10. A process according to one ofclaims 1-3 and 4 wherein said silica is precipitated silica or pyrogenicsilica or combinations thereof and said mixture contains secondaryfillers in lesser amounts than said silica, wherein said secondaryfillers are carbon black, clay, mica, talc, inorganic silicates,bentonite, titanium dioxide, aramid pulp, short vegetable fibers, shortsynthetic polymer fibers, starch, calcium carbonate, or calcium sulfateor combinations thereof, and said organic compounds are present in anamount from about 0.1 to about 30 phr.
 11. A process according to claim5 wherein said organic compound is present in an amount from about 0.1to about 30 phr, and said silica is present in an amount greater thanabout 15 phr.
 12. A process according to claim 5 wherein said silica isprecipitated silica or pyrogenic silica or combinations thereof and saidmixture contains secondary fillers in lesser amounts than said silica,wherein said secondary fillers are carbon black, clay, mica, talc,inorganic silicates, bentonite, titanium dioxide, aramid pulp, shortvegetable fibers, short synthetic polymer fibers, starch, calciumcarbonate, or calcium sulfate or combinations thereof, and said organiccompounds are present in an amount from about 0.1 to about 30 phr.
 13. Aprocess according to claim 7 wherein said organic compound is present inan amount from about 0.1 to about 30 phr, and said silica is present inan amount greater than about 15 phr.
 14. A process according to claim 7wherein said silica is precipitated silica or pyrogenic silica orcombinations thereof and said mixture contains secondary fillers inlesser amounts than said silica, wherein said secondary fillers arecarbon black, clay, mica, talc, inorganic silicates, bentonite, titaniumdioxide, aramid pulp, short vegetable fibers, short synthetic polymerfibers, starch, calcium carbonate, or calcium sulfate or combinationsthereof, and said organic compounds are present in an amount from about0.1 to about 30 phr.